﻿//-------------------------------------------------------------------------------
// <copyright file="FBSession.cs" company="TaskyMedia LLC">
//     Copyright (c) TaskyMedia LLC.
// </copyright>
//-------------------------------------------------------------------------------

/*
 * Copyright (c) 2010, TaskyMedia LLC
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *   Redistributions of source code must retain the above copyright notice, this 
 *     list of conditions and the following disclaimer.
 *   Redistributions in binary form must reproduce the above copyright notice, this
 *     list of conditions and the following disclaimer in the documentation and/or
 *     other materials provided with the distribution.
 *   Neither the name of TaskyMedia LLC nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific prior
 *   written permission.
 *   
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE. 
 */

namespace FBGraphApi
{
    using System;

    /// <summary>
    /// An authorized session in the Facebook Graph API.
    /// </summary>
    public class FBSession
    {
        /// <summary>
        /// Access token for the current authorized user.
        /// </summary>
        private string _accessToken;

        /// <summary>
        /// Initializes a new instance of the <see cref="FBSession"/> class.
        /// </summary>
        /// <param name="accessToken">The access token.</param>
        public FBSession(string accessToken)
        {
            this._accessToken = System.Web.HttpUtility.UrlDecode(accessToken);
        }

        /// <summary>
        /// Gets the access token for the current authorized user.
        /// </summary>
        /// <value>The access token.</value>
        public string AccessToken
        {
            get
            {
                return this._accessToken;
            }
        }

        /// <summary>
        /// Creates a new <see cref="FBSession" />from an OAuth token.
        /// </summary>
        /// <param name="redirectUrl">The redirect URL used in the /authorize request.</param>
        /// <param name="oauthToken">The OAuth token received from Facebook.</param>
        /// <returns>Returns an authorized session.</returns>
        public static FBSession CreateFromOAuthToken(string redirectUrl, string oauthToken)
        {
            string reqUrl = FBApiMethodUri.GetOAuthAccessToken(FBSettings.ClientId, redirectUrl, FBSettings.ClientSecret, oauthToken);

            WebRequestResult result;
            try
            {
                result = WebRequestHelper.Get(reqUrl);
            }
            catch
            {
                // Bubble up any exceptions
                throw;
            }

            if (result.Status == System.Net.HttpStatusCode.OK)
            {
                // TODO: Replace with Regular Expressions
                string data = result.Data;
                if (data.StartsWith("access_token="))
                {
                    // Pull the access token from the response data.
                    string accessToken = data.Substring(13, data.IndexOf("&", StringComparison.InvariantCulture) - 13);

                    return new FBSession(accessToken);
                }
                else
                {
                    // The response from Facebook is not accounted for.
                    // Throw an exception; for now, use InvalidOperationException.
                    throw new InvalidOperationException("The response from Facebook could not be read.");
                }
            }
            else
            {
                return null;
            }
        }
    }
}
